The present invention relates to an arrangement for a supercharged combustion engine and particularly to change air coolers for cooling compressed air which is led to the engine.
The amount of air which can be supplied to a supercharged combustion engine depends not only on the pressure of the air but also on the temperature of the air. Supplying the largest possible amount of air to a combustion engine entails the air having first to be compressed to a high pressure and thereafter to be cooled before it is led to the combustion engine. When air needs compressing to high pressure, it is advantageous that it be compressed in two stages. This may involve a compressor of a first turbo unit subjecting the air to a first compression step and a compressor in a second turbo unit subjecting the air to a second compression step. Cooling the air between the two compression steps is a known practice. The cooling of the air after it has undergone the first compression step leads to the air being at a lower temperature. The air will thus be at a lower specific volume, i.e. it will occupy a smaller volume per unit weight. As a compressor usually has a space with a constant volume in which to receive and compress air, such intermediate cooling makes it possible for a larger amount of air to be drawn into the second compressor and subjected to the second compression step. This means that a large amount of air can be compressed to a high pressure. It is also important to cool the compressed air before it is led to the combustion engine, so that a large amount of the compressed air can be led into the combustion engine.